The torque is 143 gr and good to 38 amps (Peak or Constant Unknown?) and 500 to 550 Watts.

The KV is 820 and they recommend a 13 x 6.5 on 3s

The Thrust 40 is 850KV only 140 grams and is good to 500 watts and 35 amps constant and 45 amps 10 sec burst and they recommend a 14 x 7on 3s. The Thrust motor does not specify what 4s prop to use, only that you should stay within the suggested amps.

Is the Torque motor under rated? Could you safely put a 13 x 5 or 13 x 6 on it with 4s? I would think the lower KV of the Torque would allow for higher prop sizing?

My Torque runs a 12x6 and pulls slightly over 40 amps. I suppose if you use an amp meter and are careful about it, you could, but I doubt it will turn the bigger prop. However, I have heard of guys running a 13x4 onf 4S on the Torque.

If you want to swing a big prop on 4S, the Motrolfly 2820-750 will swing a 14x7 on 4S at 7900RPM's at about 35 amps constant. My custom Motrolfy 2820-750 with 680 kv (comes stock with 630) will swing a 14x7 8200RPM's at about 45 amps producing almost 10 pounds of thrust.

OK,,,Can't resist this. I'm good at making "Half Props" so I cleaned one of these up ,,,(hacksawed it through the center),, and weighed it. The prop was a Turnigy Light Electric 16x8. I don't have one xactly like what you are testing but this method should get us some spool up data Right?
The total (half) is 20.5 grams 41gr before landing? It balances on my Buck Knife at 2.66",(67.53mm),from center hole which would be center of mass right?
Tip 6.9 gr
Ctr 13.8 gr
Center mass Dia 5.32" /135.06mm

It gained a couple grams at my Harbor Freight/ one car garage lab.
Worth while ?? or do I have to go sit in the stands?

If you want to swing a big prop on 4S, the Motrolfly 2820-750 will swing a 14x7 on 4S at 7900RPM's at about 35 amps constant. My custom Motrolfy 2820-750 with 680 kv (comes stock with 630) will swing a 14x7 8200RPM's at about 45 amps producing almost 10 pounds of thrust.

--Tom K.

Yes, I just bolted on a motrofly 2315 custom wound to 700KV. Unfortunately all I have is a Xoar 13 x 6.5. I am only getting around 37 amps and 67 ounces of thrust. I plan on getting a 14 x 7 to put on and see what I get!

OK,,,Can't resist this. I'm good at making "Half Props" so I cleaned one of these up ,,,(hacksawed it through the center),, and weighed it. The prop was a Turnigy Light Electric 16x8. I don't have one xactly like what you are testing but this method should get us some spool up data Right?
The total (half) is 20.5 grams 41gr before landing? It balances on my Buck Knife at 2.66",(67.53mm),from center hole which would be center of mass right?
Tip 6.9 gr
Ctr 13.8 gr
Center mass Dia 5.32" /135.06mm

It gained a couple grams at my Harbor Freight/ one car garage lab.
Worth while ?? or do I have to go sit in the stands?

The torque is 143 gr and good to 38 amps (Peak or Constant Unknown?) and 500 to 550 Watts.

The KV is 820 and they recommend a 13 x 6.5 on 3s

The Thrust 40 is 850KV only 140 grams and is good to 500 watts and 35 amps constant and 45 amps 10 sec burst and they recommend a 14 x 7on 3s. The Thrust motor does not specify what 4s prop to use, only that you should stay within the suggested amps.

Is the Torque motor under rated? Could you safely put a 13 x 5 or 13 x 6 on it with 4s? I would think the lower KV of the Torque would allow for higher prop sizing?

I believe ef said you could run the larger prop but you would slowly kill the motor, that is why the 12x6 was recommended.

Would it be worthwhile to know which prop would spool up the quickest? In addition to Thrust,Amps,of course. The same amount of weight farther away from the center would spool up slower. Like the Vess for instance,has wider blades toward the tips.
I think this (weighing both ends of a half prop)would be a way of determining how far from the prop shaft the center of mass is which in turn will have a barring on how fast the prop spools up.